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51316-7209-Evaluation of Full Size C110 Premium Casing Connections Fit-for-Purpose Performance in Mildly Sour Environment

The purpose of this paper is to illustrate the possibility of testing full sized connections in sour environments. It is also intended to demonstrate to the industry that the pipe body is possibly more susceptible to cracking than is the premium connection fabricated from the same susceptible material.

Product Number: 51316-7209-SG
ISBN: 7209 2016 CP
Author: Xin Long
Publication Date: 2016
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$20.00
$20.00

 

A laboratory test program was conducted to investigate full size 12 ¼ inch (311mm) OD API C110 grade premium casing connections performance in a mildly sour environment with an ID-only exposure for a fit-for-purpose study. A specially designed and built test fixture was used to conduct internal pressurizing tests of the assembled connection specimens in a controlled mildly sour solution. Two full-sized specimens (one of API C110(1) and one of API Q125) were tested. Finite element analysis (FEA) was conducted to identify high risk locations for sulphide stress cracking (SSC) for the connection specimens.

The API C110 grade premium connection and pipe body passed the test of 722 hours in the sour environment under the effective pressure. Extensive post-test examination showed no evidence of cracks in the full sized API C110 test specimen. The API Q125 grade specimen failed after only 169 hours of exposure. The crack location in the API Q125 specimen was in the pipe body while the connection pin and box were found to be crack-free. This latter result demonstrated that the premium connection is less susceptible to sour cracking than the pipe body. The location of the cracks in the API Q125 specimen agreed with FEA which showed that the highest stress locations (hot spots) are in the pipe body ID near the connection locations under caped end pressure condition.

The purpose of this paper is to illustrate the possibility of testing full sized connections in sour environments. It is also intended to demonstrate to the industry that the pipe body is possibly more susceptible to cracking than is the premium connection fabricated from the same susceptible material.

Keywords: downloadable, Connection, API C110, mildly sour environment, H2S, SSC

 

A laboratory test program was conducted to investigate full size 12 ¼ inch (311mm) OD API C110 grade premium casing connections performance in a mildly sour environment with an ID-only exposure for a fit-for-purpose study. A specially designed and built test fixture was used to conduct internal pressurizing tests of the assembled connection specimens in a controlled mildly sour solution. Two full-sized specimens (one of API C110(1) and one of API Q125) were tested. Finite element analysis (FEA) was conducted to identify high risk locations for sulphide stress cracking (SSC) for the connection specimens.

The API C110 grade premium connection and pipe body passed the test of 722 hours in the sour environment under the effective pressure. Extensive post-test examination showed no evidence of cracks in the full sized API C110 test specimen. The API Q125 grade specimen failed after only 169 hours of exposure. The crack location in the API Q125 specimen was in the pipe body while the connection pin and box were found to be crack-free. This latter result demonstrated that the premium connection is less susceptible to sour cracking than the pipe body. The location of the cracks in the API Q125 specimen agreed with FEA which showed that the highest stress locations (hot spots) are in the pipe body ID near the connection locations under caped end pressure condition.

The purpose of this paper is to illustrate the possibility of testing full sized connections in sour environments. It is also intended to demonstrate to the industry that the pipe body is possibly more susceptible to cracking than is the premium connection fabricated from the same susceptible material.

Keywords: downloadable, Connection, API C110, mildly sour environment, H2S, SSC

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Picture for Failure Investigation of a C110 Connection from a High Pressure High Temperature Well
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51314-3787-Failure Investigation of a C110 Connection from a High Pressure High Temperature Well

Product Number: 51314-3787-SG
ISBN: 3787 2014 CP
Author: David Hillis
Publication Date: 2014
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